INFORMATION CAPACITY OF ELECTRONIC VISION SYSTEMS

The comparison of various electronic-optical vision systems has been c onducted based on the criterion ultimate information capacity, C, limi ted by fluctuations of the flux of quanta. The information capacity of daylight, night, and thermal vision systems is determined first of al l by the number of picture elements, M, in the optical system. Each el ement, under a sufficient level of irradiation, can transfer about one byte of information for the standard frame time and so C approximate to M bytes per frame. The value of the proportionality factor, one byt e per picture element, is referred to systems of daylight and thermal vision, in which a photocharge in a unit cell of the imager is limited by storage capacity, and in general it varies within a small interval of 0.5 byte per frame for night vision systems to 2 bytes per frame f or ideal thermal imagers. The ultimate specific information capacity, C, of electronic vision systems under low irradiation levels rises wi th increasing density of optical channels until the number of the irra diance gradations that can be distinguished becomes less than two in e ach channel. In this case, the maximum value of C turns out to be pro portional to the flux of quanta coming from an object under observatio n. Under a high level of irradiation, C is limited by diffraction eff ects and amounts to l/lambda(2) bytes/cm(2) frame.